The present invention relates to an adjustment drive, in particular for use with adjustable flap valves.
An adjustment drive of a type involved here finds application especially in heating, air-conditioning and ventilation systems for opening and closing a control element of a flap valve. Hereby, the normal basic position may also be an intermediate position. Associated to the electromotive adjustment drive is a control unit. Some applications involve opening or closing of the control element in case of a danger, e.g. adjustment of the flap valve in case of fire. Conventional adjustment drives have wheels to form a chain of wheels which are normally supported on bolts received with their end surfaces in bores of a housing. These types of construction are labor-intensive to assemble and complicated when individual wheels have to be replaced.
It would therefore be desirable and advantageous to provide an improved adjustment drive which obviates prior art shortcomings and which is compact in structure, while yet being reliable in operation.